When the hammer of such string instruments has struck the string, it must be caught at a certain position during rebound. In conventional string instruments, the hammer is caught at a relatively great distance from the string.
The applicant's European Patent No. EP 0 500 701 B1, which is incorporated into the present patent application as reference, discloses a striking mechanism in which it is possible to catch the hammer at a relatively short distance from the string so that the strike can be repeated immediately.
Anyhow, it is important that the hammer is caught in such a way during rebound that it does not jump back and thereby spontaneously hits the string in an unintended repetition strike.
The catching of the hammer conventionally takes place when the check zone of one of the checks collides with the check zone of the other check resulting in a relatively sudden stopping of the swinging parts. Due to the inertia of the system, tensions arise in the rod system of the striking mechanism. The resultant of these tensions acts in the opposite direction of the rebound and will therefore, in some cases, be able to provoke the above-mentioned unintended repetition strike. Evidently, the risk is greatest when the catching of the hammer takes place near the string as is the case in the known structure of the applicant's above-mentioned EP Patent.
A known method for preventing the hammer, on the catching, from jumping so far back that it can restrike the string is to put a buffer in the form of usually a piece of soft felt between the check zones of the checks. Thereby, the braking of the swinging masses of the mechanism is softened, and the reactive forces in the resilient rod system of the striking mechanism become correspondingly smaller whereby the risk of the hammer being thrown back at the string is reduced.
However, it has appeared that even with, for example, a layer of felt between the check zones, unintended repetition strikes may occur. The reason for this is that it is not constructively possible to attain a sufficiently long braking length by, in this way, only mechanically braking the rebound.